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Nonlinear response history analysis (NLRHA) procedure is one of the most precise and accurate numerical method to compute the seismic demands of high-rise structures but is complex, rigorous, and time-consuming and requires a lot of expertise for nonlinear modelling and results interpretation. Therefore, practicing engineers in developing countries like Pakistan still use the simplified analysis procedures to compute the seismic demands. Among the simplified analysis procedures, equivalent lateral force and response spectrum analysis procedures are widely used for the design purpose. However, other procedures have also been proposed in the recent past to accurately capture the higher mode effects in mid-to-high-rise structures. In the current study, results of a forty-story core wall building are used to check the relative accuracy and ease of application of different simplified analysis procedures. Furthermore, a modal decomposition technique is used to separate the modal responses from the NLRHA results, and a mode wise comparison of different demand parameters for different simplified procedures is performed. The current study has been used to clearly identify the reasons of inaccuracies in different simplified procedures. Furthermore, a simplified analysis procedure is proposed to accurately estimate the seismic demands of high-rise buildings and the possible solutions to improve their predictions. [ABSTRACT FROM AUTHOR]

Precast post-tensioned concrete rocking wall system is an innovative damage avoidance structural system for seismic regions. Past experimental works on the dynamic performance of rocking walls have identified the presence of high-frequency acceleration spikes in both lateral and vertical directions during the impact of wall base with the foundation. These acceleration spikes, acting together, can cause shear slip at the wall-foundation connection. This study is focused on the development of a computer model that can predict these acceleration spikes along with the identification of their effects on the dynamic performance of rocking walls. For this purpose, impact phenomenon at the wall-foundation joint has been discussed in detail and some general guidelines are set for the two important parameters of impact or contact modeling named as contact stiffness and contact damping. The finite element numerical models, based on the proposed guidelines, are found to predict the overall dynamic behavior of rocking walls along with the acceleration spikes quite efficiently. The acceleration spikes are found to be dependent on the lateral velocity at impact and the initial contact stiffness. So a velocity-dependent energy dissipation device along with a soft contact is found to be suitable for reducing these effects. [ABSTRACT FROM AUTHOR]

Highlights: [•] Coupled walls provide superior lateral stiffness when remain elastic. [•] Coupled walls behave as stiff coupled system for wind and moderate seismic loads. [•] Coupling beams degrade prior to the plastic capacity of the system being achieved. [•] Coupled walls evolve into a collection of linked wall piers at high seismic loads. [•] Reducing coupling beam capacity could be a key in developing constructible design. [Copyright &y& Elsevier]

The use of tensile strain-hardening, high-performance fiber-reinforced concrete (HPFRC) in low-rise structural walls as a means to simplify reinforcement detailing was evaluated. To validate the proposed simplified reinforcement design, five HPFRC cantilever low-rise wall specimens with shear span-to-length ratios of either 1.2 or 1.5 were tested under large displacement reversals. For comparison purposes, four reinforced concrete (RC) walls detailed according to the seismic provisions of ACI 318-05 were also tested. The HPFRC walls had little or no confinement reinforcement in the boundary regions and reduced web distributed reinforcement compared with that in the RC walls. The RC walls exhibited drift capacities of up to 2.3%, whereas the HPFRC walls sustained drifts of up to 3%. As expected, an increase in shear stress demand led to a decrease in drift capacity for both RC and HPFRC walls. No indication of early concrete crushing or buckling of the longitudinal reinforcement was observed in the boundary regions of the HPFRC walls, even when no confinement reinforcement was provided. [ABSTRACT FROM AUTHOR]

Load-carrying capacity of confined masonry walls in the out-of-plane direction after being damaged is crucial for overall stability and is affected by the type of interface present at the wall edge and column, such as toothing. Shake table tests were conducted to investigate the effectiveness of a toothed connection on the out-of-plane behavior of damaged confined masonry walls. Four half-scale clay brick masonry walls were subjected to a sequence of slow cyclic in-plane drifts and shake table-generated ground motions in the out-of-plane direction. Specimens included one regular RC infill frame and three confined masonry panels, two with different densities of toothing and one with no toothed connection. The specimen with the infill panel demonstrated a higher risk of out-of-plane collapse, whereas the other three confined masonry wall specimens maintained structural integrity and out-of-plane stability even when severely damaged. The confined masonry walls with or without toothing enhanced the interaction between masonry walls and RC confining elements and were able to delay the failure by controlling out-of-plane deflections even after an in-plane drift cycle of 1.75%. [ABSTRACT FROM AUTHOR]